Electric starting motor



H. STEINHART'. ELECTRIC STARTING MOTOR.

APPLICATION FILED DECH'JI, I919.

Patented .Dec. 12, 1922.

BY ATI'U RNRYS Patented Dec. 12, 1922.

UNITED STATES HERMANN STEINHART, OF STUTTGART,

GERMANY, ASSIGNOR TO THE FIRM 01? ROBERT BOSCH AKTIENG-ESELLSCHAFT, OFSTUTTGART, GERMANY.

ELECTRIC STARTING MOTOR.

Application filed December 31, 1919. Serial No. 348,704.

To all whom it may concern:

Be it known that I, HERMANN STEIN- HART, a citizen of Germany, residingat and whose post-oflice address is Stuttgart, Germany, Jagerstr. 40,have invented certain new and useful Improvements in Electric StartingMotors, of which the following is a specification,

This invention relates to an electric motor for, starting internalcombustion engines which is furnished with two successively closedcircuits, that are so arranged that when the initial starting circuit isclosed, a weak current, which causes the armature to rotate slowly issupplied to it, whilst the full working current flows through the motorwhen the second or final circuit is established. The changing over fromthe first to the second circuit is performed by means of an automaticswitch.

The invention consists in a design which enables the change-over switchto be directly mounted upon the starting motor. An advantage of thisarrangement over the known method of mounting the switch separate fromthe motor consists in the parts of the starting device being reduced innumber and thus rendered easier to inspect, and in the wiring andinstallation of the equipment upon the motor-car, aeroplane or the like,being greatly simplified. The switch is preferably fixed to a supportwhich is combined with the armature bearing on the commutator side ofthe motor. This support may, for example, be made in the shape of aflange. To make the switch readily accessible it is preferably arrangedabove the commutator, where it takes up very little space and causes noaddition to the length of the machine.

The connecting devices such as cable terminals, contact plates etc., forthe switch as well as the starting motor, are all mounted on the housingof the switch, the end plate of the casing forming a support for severalterminals of this kind.

The commutator, and the automatic switch mounted above it, is enclosedin a protecting cover which is preferably provided with an openingthrough which convenient access may be had to the terminals, and whichmay be closed by a lid. This lid is preferably made of sheet metal andshaped so as to act like a spring. It is also preferably provided withprojections that click into small hollows in the protecting cover whenthe lid is pressed down onto its seat.

Tubes or sleeves, which surround the leads to the motor, are inserted inthe above-men tioned flange, that is integral with the body of thebearing adjacent to the commutator, and in order to facilitate thethreading-in and fixing of these leads in the motor terminals, the saidtubes are arranged so that their longitudinal axes, and the longitudinalaxes of the holes in the said terminals, lie in the same straight lines.

The machine shewn in the drawing, which represents a manner of carryingout the invention, is a starting electric motor with a cylindricalcasing, a coupling member (pinion) arranged to be shiftedlongitudinally, and an electromagnetically operated switch whosearmature is first caused by a mechanical power to approach its magnetpole and is then attracted magnetically only after a certainapproximation between it and the pole has been reached, when the secondor final motor circuit will be established.

Fig. 1 shows a front elevation of the motor, partly in longitudinalsection,

Fig. 2 is end view as seen from pinion end of the machine,

Fig. 8 is a section on the line m of Fig. 1,

Fig. at is section of the protecting cover and its lid on an enlargedscale and Fig. 5 is a diagram of the circuits of the starting motor.

As shewn in Figs. 1 and 3 the automatic switch a is arranged above thecommutator b of the starting motor 0. The housing a of the switch a isfastened by screws a" to a flange (Z. which is integral with the body fof the bearing that is attached to the commutator end 6 of the motorcasing. lVhen thus mounted the switch a and its housing a take up verylittle space and do not add to the length of the machine. An extension9' of the end plate 9 running at right angles to the plate, bears uponthe top surface of the housing a, of the switch. Mounted upon theextension 9 are several conductor-connecting-devices (terminals) 1, 2, 3and some contact plates 4, 5, 6 are arranged upon the front of the plateg. The functions of these terminals and contact plates will be describedlater in connection with the circuits shewn in Fig. 5.

was

inserted in the flange (Z oi the commutator bearing are leading-in tubesit If, it" of insulating substance. The axis 01' the tube il and thatoi"? the hole in tern'zina-l 1 lie in a straight line and the tubes 71and the holes in the terminals 2, 3 have also common longitudinal axes,this arrangement enabling the wires or leads inserted throv the leadinin tubes 72, 729, its to be easny threaded into and fixed in theterminals 1, 2, 1-3. To limit as far as possible the restraint as to thed' otion in. which the wires may be led up and into, ie motor,leading-in tubes siln'lar to ma als be provided in the end. wall oi theprotecting cover '2 that is opposite to the flange cl.

i or the handling of the terminals 1. 2. 3 and others which are attachedto the switch housing a, it not necessary to remove the nro'te cover ithat incloscs the commutator l) and the switch a, because an open.- ingin the cover 2' is provided above the switch which is closed by aneasily removed lid Z2. This lid consists of sheet metal. which is shapedso as to act like a spring. It has bent ears Z or other suitablettensions which, on the lil being pressed down onto its seat, are causedby the spring action of the lid to click into corresponding cavities min the cover. For the convenient removal of the lid. pockets at areprovided at both sides for the insertion of the fingers.

The mode of operation of the switch a, and the significance of thevarious terminals and contact plates shewn in Figs. 1 and 3, will beevident from the circuits illustrated in Fig. 5.

In this A denotes the armature of the starting motor, E its main fieldwinding, ll an auxiliary field winding, a the automatic switch. l d itscoil. B the battery, the pri mary coil of the ignition apparatus for theinternal combustion engine, V the ipnition amplifier. and D a pressbutton switch.

(in the closure of the press button switch D a current flows from thebattery through the press button switch. terminal. 2 of the switch a,magnet coil M of this switch. terminal '7, and, at first. through theauxiliary winding H only to the motor armature A and thence through thebody of the machine bar-1r to the battery. On account of thecomparatively laroe resistance of the auxiliary field WlllCllHQj H themotor armature a receives only a small current so that it only rotatesslowly. But the auxiliary field windingalso exercises an attractivemagnetic force upon the armature A of the starting; motor, which isnormally kept displaced from the field between the pole faces by aspring, so that the pinion r (Fig. l)

is held out of engagement with the circle of teeth on the flywheel oithe internal combustion engine that. is to be star ed by the motor. Whenthe motor armature, whilst a inst nose 3) (Fig. 1) which attached to arod 3 the. is fixed to the armature g (see Fig. ot the switch Hence,after the motor arm: re has moved a certain distance in the direction ofthe :i is made to participate in this and the a enough to the magnetpole of the o to pe mit of the armature 9 being c netirally a These arethe func- 'ons performed during the first stage oi operation of theswitch.

l vhen the switch armature q is fully attracted, it causes the closureof the second or final motor circuit by interconnecting the contactplates 4, 6 with the aid of the brush t mounted upon the end of thearinature lln addition to the circuit already described, supplementalcircuit is now closed in which current flows through the terminal, 1 onthe switch housing a, contact plate 4 on the end plate 9' of the switchhousing, brush 2?, contact plate 5, terminal 8, and main field winding Eto the motor armature l he main and auxiliary field windings are nowconnected in parallel so the effect of the auxiliary winding? is addedto that. of main field winding; The startinp; motor now receives itsfull or nornial workingcurrent and by means of the pinion a" it exerts apowerful torque on the flywheel oi. the internal combustion engine.

Another branch circuit may be traced roiu the battery through thecontact plate and the terminal 3- to the amplifier V and the primarycoil P of the ignition apparatus. 7

l claim:

l. in combination with any internal com bustion engine, an electricstarting; motor having an armature. initial circuit and a final circuitfor said motor, a switch for changing: over from the said initialstarting circuit to the final circuit. a housing for said switch,terminals for the switch and motor a commutator, an armature bearingadjacent to the commutator, support attached to said armature bearing,means for mounting; said housing; of d switch on the support at theupper side of the commutator, said housins: carrying said terminals.

2. in combination with an internal combustion engine. an electricstarting motor having an armature, an initial circuit and a finalcircuit tor said motor, a switch :tor changing; over tromthe saidinitialstarting TOO. armature g is thus brought circuit to thefin al circuit,terminals for the switch and motor having holes therein for ill)receirirq conductors, a housing for said switch, a commutator, anarmature bearing adjacent to the commutator, a support attached to saidarmature bearing, means for mounting said housing of said switch on thesupport at the upper side of the commutator, said housing carrying saidterminals, and leading in tubes arranged in said support with theirlongitudinal axes coincident with the axes of the conductor receivingholes in said terminals.

In combination with an internal combustion engine, an electric startingmotor having an armature, an initial circuit and a final circuit forsaid motor, a. switch for changing over from the said initial startingcircuit to the final circuit, a housing for said switch terminals forthe switch and motor, a commutator, an armature bearing adjacent to thecommutator, a support attached to said armature bearing, means formounting said housing of said switch on the support at the upper side ofthe said commutator, said housing carrying said terminals, and a coverenclosing the said commutator and switch, said cover having an openingafi'ord ing access to this switch, and a removable lid associated withsaid opening.

In testimony whereof I have affixed my signature in )resence of twowitnesses.

ERMANN STEINHART. Witnesses:

ADOLPH SEBERERS, J. MARKUS MEYER.

